Blower and heatpump using the same

ABSTRACT

A now-noise blower is provided which reduces the turbulence of incoming air flow itself even if there is un-uniformity resulting from circumferential positions around a rotation shaft of air inlet passage. Such a blower includes a blade  1  having its outer circumferential edge  1   c  warped in a rotational direction and a bellmouth  5  covering the circumference of the blade at the air outlet side, wherein a surface of the bellmouth facing the blade has a convex-shaped first upstream expanding portion  5   c  upstream extending from a minimum inner diameter portion Pb 3  and a concave-shaped second upstream expanding portion  5   d  further upstream extending, the second upstream expanding portion being continuous from the first upstream expanding portion.

TECHNICAL FIELD

The present invention relates to a propeller fan type blower providedwith a bellmouth and an impeller and to a heat pump apparatus using sucha blower and, more particularly, to improvement of a bellmouthstructure.

BACKGROUND ART

In order to provide a low-noise blower, it is necessary to minimize aturbulent air flow coming into a blower. Until now, various efforts havebeen made to improve the shape of a bellmouth to reduce blast noiseemissions from a blower provided with a bellmouth and an impeller. Forexample, there has been proposed a bellmouth that increases a diameterin a bending fashion toward an upstream side from a straight pipesection having the smallest bellmouth diameter and has a straightsection formed radially outwardly from its edge. Even if an air flowseparation takes place at a rim of such a straight section, such airflow again attaches to the inner surface of the straight section whileflowing therealong, and thereafter smoothly moves and is inhaled intothe bellmouth, thereby reducing blast noise emissions (for example, seePatent Document 1).

Also, there has been proposed a bellmouth which has an inlet side wallhaving a cross-sectional shape which is a almost semi-circular shapecurved toward a radially outward direction from the inner surface of aninlet opening, thereby suppressing separation of air flow at the inletopening to reduce noise emissions when operating a fan (for example,Patent Document 2).

A bellmouth shape is proposed in such a way that, while keeping a frontpanel of the outdoor unit of an air conditioning apparatus rectangular,by changing the magnitude of a curvature of the upstream diameterexpanding curved portion from the portion having the minimum bellmouthinner diameter in accordance with the distance between the top, bottom,left, and right peripheral side plates of a surrounding outdoor unitenclosure and the outer circumference of the impeller, an orifice shapecan be set in accordance with a different inflow air flow angle in thevicinity of the impeller, separation of flow is reduced in the vicinityof the orifice, so that low noise is achieved. (For example, refer toPatent Document 3.)

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2003-184797 (FIGS. 1 to 3)

[Patent Document 2] Japanese Patent No. 3084790 (FIGS. 1 and 2)

[Patent Document 3] Japanese Patent No. 2769211 (FIGS. 2 and 3)

DISCLOSURE OF INVENTION Problems To Be Solved By the Invention

A bellmouth having a radially outwardly extending straight sectionformed at the rim, or having its inlet side wall curved in an almostsemi-circular shape toward a radially outward direction from the innersurface of an inlet opening so as to reduce separation of air flow onthe bellmouth incoming from the outer circumferential edge of a bladesuch as air flow incoming from a region concealed by the bellmouth whenseen from a blade of the blower, can fulfill its function only when theblower is used under an ideal air passage environment, that is, anenvironment where air passage is circumferentially uniform about itsrotation shaft. However, such an ideal air passage environment is rareas an actual air passage where the blower is operated. In addition, evenif the air passage is circumferentially uniform about the rotationshaft, air flow coming into a blower is hardly stable and uniform. Infact, incoming air flow is always changing and significantly turbulentwhen viewed from a rotating blade, which makes it difficult for a blowerto sufficiently fulfill its function.

Further, a blower having a bellmouth whose curvature changes accordingto un-uniformity resulting from a circumferential position of an inletside air passage just reduces separation on the bellmouth, and is noteffective in reducing the turbulence of incoming air flow, assuming thatsuch a blower is mounted on an air conditioning apparatus.

An objective of the present invention is to reduce the turbulence ofincoming air flow itself to obtain a low noise blower even if there isun-uniformity resulting from circumferential positions about therotation shaft of the inlet side air passage.

Means For Solving the Problems

A blower according to the present invention comprises;

a blade having an outer circumferential edge having a recessed warp in arotational direction, and

a bellmouth covering the circumference of the blade at an air outletside,

wherein a surface of the bellmouth facing the blade has a first upstreamexpanding portion formed in a shape of a convex in an upstream directionof a rotation shaft, extending upstream from a minimum inner diameterposition and a second upstream expanding portion formed in a shape of aconcave in the upstream direction of the rotation shaft, beingcontinuous with and extending upstream from the first upstream expandingportion.

Advantages

In a blower according to the present invention, a surface of thebellmouth facing the blade has a first upstream expanding portion formedin a shape of a convex in an upstream direction of a rotation shaft,extending upstream from a minimum inner diameter position and a secondupstream expanding portion formed in a shape of a concave in theupstream direction of the rotation shaft, being continuous with andextending upstream from the first upstream expanding portion, wherebythe outer circumferential edge of the blade is enclosed and a distancebetween the outer circumferential edge and the bellmouth becomes wider.This allows more air to be drawn in from around the outercircumferential edge, thereby preventing a pressure change on thebellmouth surface arising from turbulence by the blade tip vortex. Inaddition, this allows air passage around the outer circumferential edgeof a blade to be circumferentially uniform, which suppresses fluctuationof air flow coming into the blade, leading to the achievement of alow-noise blower. Furthermore, this allows a section from the secondupstream expanding portion to the minimum inner diameter point to form asmoothly continuous shape, which suppresses the turbulence of the airflow itself and effectively reduces noise levels.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of a blower according to Embodiment 1 of thepresent invention, as viewed from an outlet opening.

FIG. 2 is a cross-sectional view taken along the line A-A of FIG. 1.

FIG. 3 is a cross-sectional view taken along the line B-B of FIG. 1,whose outer circumferential edge is developed into a plane with linesindicating a position of each part in a bellmouth.

FIG. 4 is an enlarged partial view of FIG. 2.

FIG. 5 is the same view as FIG. 3, with the addition of a lineillustrating the state of airflow in the vicinity of an outercircumferential edge of a blade.

FIG. 6 is the same view as FIG. 2, with the addition of lines indicatinga conventional bellmouth for comparison.

FIG. 7( a) is a front view of an outdoor unit of an air conditioningapparatus according to Embodiment 2, 6 of the present invention. FIG. 7(b) is a cross-sectional view taken along the line C-C.

FIG. 8 is a view showing the direction of an air passage, as seen fromthe rotational shaft of an outdoor unit of an air conditioning apparatusaccording to Embodiment 2, 6 of the present invention,

FIG. 9( a) is a front view of an outdoor unit of an air conditioningapparatus according to Embodiment 3 of the present invention. FIG. 9( b)is a cross-sectional view taken along the line D-D. FIG. 9( c) is across-sectional view taken along the line E-E.

FIG. 10 is a view showing the direction of an air passage, as seen fromthe rotational shaft of an outdoor unit of an air conditioning apparatusaccording to Embodiment 3 of the present invention.

FIG. 11 is a partially enlarged cross-sectional view of a main sectionof a bellmouth and a propeller fan, as seen from an inlet side.

FIG. 12( a) is a front view of an outdoor unit of a heat pump waterheater according to Embodiment 4 of the present invention. FIG. 12( b)is a cross-sectional view taken along the line F-F. FIG. 12( c) is across-sectional view taken along the line G-G.

FIG. 13 is an enlarged view of a main section of a blower according toEmbodiment 5 of the present invention.

FIG. 14 is a view obtained by developing an outer circumferential edgeof a blade of a blower according to Embodiment 5 of the presentinvention into a plane with the addition of leader lines indicating aposition in a bellmouth as well as those indicating the state of airflow in the vicinity of the outer circumferential edge of a blade.

FIG. 15 is an enlarged view of a main section of a blower according toEmbodiment 5 of the present invention, with a comparison withconventional one.

FIG. 16 is a comparison chart of aerodynamic noise properties of a heatpump apparatus according to Embodiment 7 of the present invention withconventional one.

FIG. 17 is a comparison chart of aerodynamic noise properties of a heatpump apparatus according to Embodiment 7 of the present invention withconventional one.

FIG. 18 is a diagram showing the shape of a blade of a propeller fanaccording to Embodiment 7 of the present invention.

FIG. 19 is a diagram showing the shape of a blade of a propeller fanaccording to Embodiment 7 of the present invention.

REFERENCE NUMERALS

1 blade

1 c outer circumferential edge

Pb3 minimum inner diameter position

Pb4 point (transition position)

Pf3 maximum warpage position

5 bellmouth

5 c first upstream expanding portion

5 d second upstream expanding portion

5 e third upstream expanding portion

13 air outlet face

15 heat exchanger (side face)

17 top face of enclosure

18 bottom plate (side face)

22 separation plate (side face)

23 end warpage (curved surface)

BEST MODES FOR CARRYING OUT THE INVENTION Embodiment 1

Embodiment 1 of the present invention is described below with referenceto the accompanying drawings.

FIG. 1 is a front view of a blower according to Embodiment 1 of thepresent invention, as viewed from an outlet opening. FIG. 2 is across-sectional view taken along the line A-A of FIG. 1. FIG. 3 is across-sectional view taken along the line B-B of FIG. 1, whose outercircumferential edge is developed into a plane with lines indicating aposition of each part in a bellmouth. FIG. 4 is an enlarged partial viewof FIG. 2. FIG. 5 is the same view as FIG. 3, with the addition of aline illustrating the state of airflow in the vicinity of an outercircumferential edge of a blade. FIG. 6 is the same view as FIG. 2, withthe addition of lines indicating a conventional bellmouth forcomparison.

In a blower according to the present embodiment, a propeller fan 3having a plurality of blades 1 around a hub 2 is driven by a fan motor7. The blade 1 is formed of a joining edge with the hub 2, a leadingedge 1 a facing a rotational direction, a trailing edge 1 b opposed tothe leading edge 1 a, an outer circumferential edge 1 c, which isopposed to the joining edge and connecting the leading edge 1 a and thetrailing edge 1 b, and a curved surface surrounded by these joiningedges, the leading edge 1 a, the trailing edge 1 b, and the outercircumferential edge 1 c. The blade 1 has a pressure surface 1 d facingthe rotational direction 10 formed at one side thereof and anegative-pressure surface 1 e formed at the other side thereof. Pf1 is apoint at the intersection of the leading edge 1 a with the outercircumferential edge 1 c, while Pf2 is a point at the intersection ofthe trailing edge 1 b with the outer circumferential edge 1 c. The outercircumferential edge 1 c has a concave warpage in the rotationaldirection, as shown in FIG. 3. Pf3 represents a maximum warpage positionat which the distance between a chord 4 connecting Pf1 and Pf2 and theouter circumferential edge 1 c is the largest.

In FIGS. 2 and 4, lines of the blade 1 show a rotational trajectory ofthe leading edge 1 a, the trailing edge 1 b, and the outercircumferential edge 1 c. A shaft about which the fan motor 7 and thepropeller 3 rotate is referred to as a rotational shaft. A directiontoward the air inlet side of the rotational shaft (the left side of FIG.2) is set as an upstream direction of the rotation shaft, while adirection toward the air outlet side of the rotational shaft (the rightside of FIG. 2) is set as a rotational downstream direction of therotation shaft.

The outer periphery of the air outlet of the blade 1 is covered with abellmouth 5. As shown in FIG. 4, the bellmouth 5 is located so as tocover the entire blade outer circumference or part of the trailing edge1 b. When classifying characteristics of each section of the bellmouth 5by a cross-section shape in the blade side face, a section between Pb2and Pb3 is a minimum inner diameter portion 5 b that is the closest tothe outer circumferential edge 1 c of the blade 1 so as to cover thetrailing edge 1 b of the outer circumference edge 1 c of the blade 1. Asection from Pb2 to a Pb1 curves to form a downstream of expandingportion 5 a for expanding an air passage toward the rotationaldownstream of the rotation shaft direction, and at Pb1 connects to abaffle plate 6 for separating an air outlet space β from an air inletspace α.

The bellmouth 5 has the following air passage expanding shape(contraction flow shape as seen from the air flow direction)in the inletside direction. The bellmouth 5 has a convex shaped first upstreamexpanding portion 5 c between Pb3 and Pb4, Pb3 being an upstream end ofthe rotation shaft of the minimum inner diameter portion 5 b of thebellmouth 5. The bellmouth 5 has a concave shaped second upstreamexpanding portion 5 d from Pb4 to Pb5, which follows the first upstreamexpanding portion 5 c. The second upstream expanding portion 5 d has alarge curvature in the vicinity of Pb4, while it has a small curvaturein the vicinity of Pb5, and has a substantially conic section in thevicinity of Pb5. In addition, the bellmouth 5 has a convex shaped thirdupstream expanding portion 5 e from Pb5 to Pb6, which follows the secondupstream expanding portion 5 d.

Next, the positional relationship in the rotational shaft directionbetween the propeller fan 3 and the bellmouth 5 is described below withreference to FIGS. 3 and 4. Dashed lines Lb3, Lb4, Lb5, and Lb6 in FIG.3 represent positions of Pb3, Pb4, Pb5, and Pb6 in the rotational shaftdirection in the bellmouth 5, respectively. In FIG. 4, a dashed line Lf3represents a position in the rotational direction of the maximum warpageposition Pf3 on the outer circumferential edge 1 c of the blade 1. Pb3,the upstream end of the rotation shaft of the minimum inner diameterportion 5 b of the bellmouth 5, is located upstream of the rotationshaft direction of the trailing edge end Pb2 in the outercircumferential edge 1 c of the blade 1. Pb4 in the transition portionbetween the first upstream expanding portion 5 c and the second upstreamexpanding portion 5 d of the bellmouth 5 is located downstream of therotation shaft direction of the maximum warpage position Pf3 on theouter circumferential edge 1 c of the blade 1. In other words, aposition in the rotation shaft direction of the maximum warpage positionPf3 on the outer circumferential edge 1 c of the blade 1 is includedwithin the range covered by the second upstream expanding portion 5 d.

The operation of a blower according to the present embodiment isdescribed using FIGS. 1 to 5.

In the blower having the structure described above, the propeller fan 3,when driven by the fan motor 7, sends to the air outlet space β the airinside a region where the propeller fan 3 rotates and at the same timedraws in the air in the air inlet space α to the region where thepropeller 3 rotates. Gases enter the propeller fan 3 from the faceformed of a rotational trajectory of the leading edge 1 a and the faceformed of the rotational trajectory of the outer circumferential edge 1c. In this way an air flow from the inlet side space α to the outletside space β takes place.

As shown in FIG. 5, part of the gas entering the propeller fan 3 becomesa leak flow 8 to a negative pressure surface 1 e from a pressure surface1 d via the outside of the outer circumferential edge 1 c. A flow havinga vortex structure called a blade tip vortex 9 takes place at a positionalong the outer circumferential edge 1 c of the negative pressuresurface 1 e, originating from the leak flow 8 occurring in the vicinityof the leading edge of the outer circumferential edge 1 c. The blade tipvortex 9 becomes larger as it moves toward the trailing edge side fromthe leading edge side, and moves away from the outer circumferentialedge 1 c in the vicinity of the maximum warpage position Pf3 at which aflow deflection becomes large. The blade tip vortex 9 having moved awayfrom the outer circumferential edge 1 c is pushed by the entire flowfrom the inlet side space α to the outlet side space β to graduallyproceed to the outlet side space β and is discharged out of the bloweras the structure of the vortex weakens.

The positional relationship in the downstream side between the bellmouth5 and the outer circumferential edge 1 c is described below. In orderfor the blower to generate a required flow rate, a pressure differenceshould be maintained between the inlet side space α and the outlet sidespace β depending upon the flow rate. The portion at which the distancebetween the blade 1 and the bellmouth 5 is smallest is the gap betweenthe minimum inner diameter portion 5 b from Pb2 to Pb3 and the outercircumferential edge 1 c. In the present embodiment, such a gap is setat a position in the vicinity of the trailing edge 1 b of the outercircumference edge 1 c. If the gap is too large, the required pressuredifference and flow rate cannot be attained when there is a greater airflow resistance before and after the blower. Accordingly, the presentembodiment makes the gap between the bellmouth 5 and the blade 1 in thevicinity of the trailing edge 1 b of the outer circumferential edge 1 csmaller. Preferably, the gap is about one to three percent of the bladeouter diameter (diameter of a rotation circle of the outercircumferential edge 1 c).

The positional relationship in the upstream side between the bellmouth 5and the outer circumferential edge 1 c is described below. As describedabove, the face composed of the rotational trajectory of the outercircumferential edge 1 c of the blade 1 is an air inlet face. Receivingincoming flow from a larger inlet area has an effect to reduce incomingflow speed at the same flow amount and reduce noise levels. Accordingly,it is preferable to make the distance between the outer circumferentialedge 1 c of the blade 1 and the bellmouth 5 sufficiently wide. The outercircumferential edge 1 c of the blade 1 is also a place where the bladetip vortex 9 originates, grows, and moves away. The blade tip vortex 9has large turbulence, and, if there is a wall such as a bellmouth 5 inthe vicinity, a pressure change on the wall surface becomes so largethat results in an increase in noise. To prevent these problems, it ispreferable to make the distance between the bellmouth 5 and the outercircumferential edge 1 c of the blade 1 in the upstream sidesufficiently large.

A blower for practical use, however, it is quite rare that there is awide area around the blade 1 in the inlet space α and the blade has acircumferentially uniform shape. Air flow to the blade tends to becomecircumferentially nonuniform and varies in terms of time, as seen fromthe rotating blade 1, causing an increase in noise. Accordingly, inorder to achieve a low-noise blower, it is preferable to provide acircumferentially uniform air passage shape. More preferably, the outercircumferential edge 1 c of the blade 1 is covered with the bellmouth 5.

In order to achieve a low-noise blower while maintaining the pressuredifference between the inlet space α and the outlet space β, it ispreferable to narrow the distance between the outer circumferential edge1 c of the blade 1 and the bellmouth 5 in the vicinity of the trailingedge 1 b and to secure a wider space at a position closer to theupstream side to take in more air flow. In addition, in order to preventa pressure change on the bellmouth wall surface resulting from the bladetip vortex 9, it is preferable while covering the outer circumferentialedge 1 c of the blade 1 to widen the distance between the outercircumferential edge 1 c of the blade 1 and the bellmouth 5 to suppressan increase in noise arising from the nonuniform air passage shape.

In a blower according to the present embodiment, since following aconvex-shaped first upstream expanding portion 5 c formed upstream ofthe rotation shaft, there is the concave-shaped upstream secondexpanding portion 5 d formed upstream of the rotation shaft, as isevident from FIG. 6, it is found that the distance between the outercircumference 1 c of the blade 1 and the bellmouth 5 can be made largerwhile surrounding the outer circumference 1 c of the blade 1 than theupstream expanding shape in a convex-shaped curved section 11 (shown bydashed line in the figure) upstream of the rotation shaft from innerdiameter minimum portion conventionally employed in general. This allowsmore air to be drawn in from around the outer circumferential edge 1 cof the blade 1, thereby preventing a pressure change in the bellmouthsurface resulting from turbulence by the blade tip vortex 9. Inaddition, this allows air passage around the outer circumferential edge1 c of a blade 1 to be circumferentially uniform, which suppressesfluctuation of air flow coming into the blade 1, leading to theachievement of a low-noise blower. Furthermore, this allows a sectionfrom the upstream of the rotation shaft direction of the second upstreamexpanding portion 5 d to the minimum inner diameter point Pb3 to form asmoothly continuous shape, which is effective in suppressing theturbulence of air flow and efficiently reduces noise.

Furthermore, the second upstream expanding portion 5 d has a largecurvature close to the first upstream expanding portion 5 c and asmaller curvature at more upstream position and has a substantiallyconic section at the upstream portion, which allows for a wider openingarea upstream of the rotation shaft of the second upstream expandingportion 5 d, thereby guiding a large amount of air flow to the spacebetween the outer circumferential edge 1 c and the bellmouth 5. Thisenables a large-air-capacity, low-noise blower to be implemented. Inaddition to the second upstream expanding portion 5 d, the blower has aconvex-shaped third upstream expanding portion 5 e upstream of therotation shaft. The blower allows air entering from the end of thebellmouth to follow the third upstream expanding portion 5 e forreduction in turbulence and guides it to the blade 1. As a result, amuch lower-noise blower can be obtained.

An advantage of the relationship between the warpage of the outercircumferential edge 1 c of the blade 1 and the expanded shape of thebellmouth 5 in the blower according to the present embodiment isdescribed below. The blade tip vortex 9 undergoes significantfluctuation in the vicinity of the maximum warpage where the blade tipvortex grows and moves away, having great influence on a pressure changeon the bellmouth wall surface. Here, the bellmouth 5 has the transitionpoint Pb4 between the first upstream expanding portion 5 c and thesecond upstream expanding portion 5 d located downstream of the maximumwarpage position Pf3 on the outer circumferential edge 1 c of the blade1, which results in a large distance between the outer circumferentialedge 1 c of the blade 1 and the bellmouth 5 in the vicinity of themaximum warpage point Pf3, thereby suppressing a pressure change on thebellmouth wall surface.

In addition, the location in the rotation shaft direction of the maximumwarpage point Pf3 on the outer circumferential edge 1 c of the blade 1falls within the range covered by the second upstream expanding portion5 d, which reduces turbulent air flow around the blade tip vortex 9 whenit moves away and also reduces the turbulence of the blade tip vortex 9,thereby suppressing the noise caused by the moving blade tip vortex 9.

Descriptions will be given to the case when the location in the rotationshaft direction of the maximum warpage point Pf3 on the outercircumferential edge 1 c of the blade 1 falls within the range coveredby the second upstream expanding portion 5 d. A similar advantage isalso provided when the maximum warpage point Pf3 is located within therange covered by the third upstream expanding portion 5 e.

Embodiment 2

FIGS. 7 and 8 show a heat pump apparatus, namely an air conditioningapparatus according to Embodiment 2 of the present invention. FIG. 7( a)is a front view of a box-shaped outdoor unit of an air conditioningapparatus, while FIG. 7( b) is a cross-section taken along the line C-Cof FIG. 7( a). FIG. 8 is a view showing the direction of air passage, asseen from the rotation shaft. The reference numerals and symbols in FIG.7 refer to the same components as those with the same numerals andsymbols in the above-described Embodiment 1. Reference is also made toFIGS. 1 to 6 when describing a blower.

An air conditioning apparatus, namely, a box-shaped outdoor unit 12according to the present embodiment includes an air outlet face 13formed in the front face, an air inlet face 14 formed at two facesincluding its opposite face (back face) and one face on the left-handside, and a L-shaped heat exchanger 15 disposed so as to cover the airinlet face 14. A blower is disposed close to the heat exchanger 15. Sucha blower includes a blower according to above described Embodiment 1.The heat exchanger 15 includes a pipe having a multilayer fin for heatdissipation formed on an outer surface thereof, the pipe having arefrigerant circulating thereinside. The heat exchanger 15 does notnecessarily have an L-shaped form, and may be provided on a back faceonly. In such a case, the side surrounding the air outlet face 13 on thebox-shaped unit is formed of a plurality of side plates.

A grill 16 is disposed downstream of the rotation shaft of the blower,which protects a propeller fan 3 or protects a person from the rotatingpropeller fan 3. The air outlet face 13 and the bellmouth 5 aresurrounded by the heat exchanger 15, top plate 17, bottom plate 18, andseparating plate 22. The separating plate 22 separates an inboard airpassage chamber 19 housing the blower inside the outdoor unit 12 from acompressor chamber 21 housing a compressor 20.

As shown in FIG. 3, a blade 1 of the propeller fan 3 has aconcave-shaped warpage in the outer circumferential edge 1 c in therotational direction 10. As described in FIG. 4, with the bellmouth 5surrounding the entire periphery side of the blade or trailing edge sideof the propeller fan 3, a minimum inner diameter portion 5 b having theshortest distance with the outer circumferential edge 1 c of the blade 1in the section from Pb2 to Pb3, covers a trailing edge 1 b of the outercircumferential edge 1 c in any of directions (i) to (viii) shown inFIG. 8. A downstream expanding portion 5 a is provided whose air passagebends at a section from Pb2 to Pb1 to expand in the rotation shaftdownstream direction. The air passage expanding shape (contraction flowshape as seen from the air flow direction) in the inlet directionincludes a convex shaped first upstream expanding portion 5 c betweenPb3 and Pb4, Pb3 being an end point of upstream direction of therotation shaft of the minimum inner diameter portion 5 b. Also, thebellmouth 5 has a concave shaped second upstream expanding portion 5 dfrom Pb4 to Pb5 upstream of the rotation shaft, which follows the firstupstream expanding portion 5 c. The second upstream expanding portion 5d has a large curvature in the vicinity of Pb4, while it has a smallcurvature in the vicinity of Pb5, and has a substantially conic sectionin the vicinity of Pb5, which is an upstream portion. Furthermore, thebellmouth 5 has a convex shaped third upstream expanding portion 5 e ina section from Pb5 to Pb6, which follows the second upstream expandingportion 5 d.

As described in FIG. 4, in the rotation shaft direction of the propellerfan 3 and the bellmouth 5, Pb3, an upstream end of the minimum innerdiameter portion 5 b of the bellmouth 5 in the rotation shaft direction,is located upstream of the rotation shaft direction of the trailing edgeend Pb2 in the outer circumferential edge 1 c of the blade 1. Pb4 in thetransition between the first upstream expanding portion 5 c and thesecond upstream expanding portion 5 d is located downstream of therotation shaft of the maximum warpage position Pf3 on the outercircumferential edge 1 c of the blade 1. In other words, a position inthe rotation shaft direction of the maximum warpage position Pf3 on theouter circumferential edge 1 c of the blade 1 falls within the rangecovered by the second upstream expanding portion 5 d.

An air conditioning apparatus, namely an outdoor unit 12 according tothe present embodiment is described with regard to operation. Whendriven by the fan motor 7, the propeller fan 3 rotates to send the airinside the inboard air passage chamber 19, a region where the propellerfan 3 rotates, from the air outlet face 13 to the air outlet space β,and at the same time draws in the air in the air inlet space α from theair inlet face 14 through the fin of the heat exchanger 15, which entersthe inboard air passage chamber 19 where the propeller fan 3 rotates.The heat exchanger 15 include a refrigerant having higher or lowertemperature than the gas outside the exchanger circulating thereinside,providing heat exchange when the air outside the exchanger 15 passestherethrough. The air, which becomes warmer or colder after undergoingheat exchange by the heat exchanger 15 when entering the inboard airpassage chamber 19, is blown out to the outside with the rotatingpropeller fan 3.

Air flow around the blade of the propeller fan 3 behaves in the samemanner as that in Embodiment 1. That is, as shown in FIG. 5, part of theair entering the propeller fan 3 becomes a leak flow 8 to the negativepressure surface 1 e from the pressure surface 1 d via the outside ofthe outer circumferential edge 1 c. A blade tip vortex 9 takes place ata position along the outer circumferential edge 1 c of the negativepressure surface 1 e, originating from the leak flow 8 occurring in thevicinity of the leading edge of the outer circumferential surface 1 c.The blade tip vortex 9 grows as it transits to the trailing edge sidefrom the leading edge side, and moves away from the outercircumferential edge 1 c of the blade in the vicinity of the maximumwarpage position Pf3 at which a flow deflection becomes large. The bladetip vortex 9 that left the outer circumferential edge 1 c is pushed byan entire flow from the inboard air passage chamber 19 to the outside ofthe unit and is discharged out of the blower through the air outlet face13, while weakening its vortex structure.

As described above, since an air conditioning apparatus according to thepresent embodiment employs the blower described above in Embodiment 1 asa blower for promoting heat exchanger by the heat exchanger 15 in theoutdoor unit 12, it is characterized by the shape of the bellmouth 15around the propeller fan 3 and the positional relationship between thepropeller fan 3 and the bellmouth 5. Accordingly, in the same way aswith the above described Embodiment 1, a great amount of air can bedrawn in from the outer circumferential edge 1 c of the blade 1 of theblower, which suppresses a pressure change on the surface of thebellmouth 5 arising from turbulence of the blade tip vortex 9. Inaddition, air passage around the outer circumferential edge 1 c of theblade 1 can be circumferentially homogenized, which helps to suppressfluctuation of air entering the blade 1, leading to the achievement of alower-noise blower.

A section between the upstream side of the rotation shaft of the secondupstream expanding portion 5 d and the Minimum inner diameter point Pb3can be constructed into a smoothly continued shape, which effectivelysuppresses turbulent of air flow and efficiently reduces noise. Inparticular, in a box-shaped outdoor unit 12, the distance to the end ofair passage except the bellmouth 5 seen from the blade 1 is small, forexample, in the direction of (i), (iii), (v), or (vii) in FIG. 8 andlarge in the direction of (ii), (iv), (vi), or (viii). An outdoor unitemploying a conventional blower which has no sufficient distance betweenthe bellmouth 5 and the maximum warpage position Pf3 on the outercircumferential edge 1 c of the blade 1 experiences significantfluctuation in incoming flow and the blade tip vortex 9 due to thechange in air passage distance resulting from the rotation position ofthe blade 1. However the outdoor unit 12 employing a blower according tothe present embodiment having a sufficient distance between thebellmouth 5 and the maximum warpage position Pf3 on the outercircumferential edge 1 c of the blade 1 is capable of preventingfluctuation of incoming flow of the air passage distance resulting fromthe rotation position of the blade 1, leading to a significant reductionin noise.

Also, a change in air flow at the rotational position of the blade 1 canbe reduced, which results in reduction of a change of force exerted bythe propeller fan 3 on the fan motor 7, leading to reduction of bearingwear or shaft deflection of the fan motor 7. This prolongs thedurability of the outdoor unit 12 and helps to achieve the outdoor unit12 that provides a stable quality during a long period of service.

Embodiment 3

In the above-described Embodiment 2, an air conditioning apparatus as aheat pump is described which has a bellmouth 5 around a propeller fan 3,the bellmouth 5 having a second upstream expanding portion 5 d formed atthe circumferential surface thereof and a third upstream expandingportion 5 e formed upstream of the second upstream expanding portion 5d. An objective of the present invention can also be achieved by formingthe second upstream expanding portion 5 d and the third upstreamexpanding portion 5 e only at a portion where the distance to the end ofan air flow passage other than the bellmouth 5 seen from the blade 1rapidly changes in the circumferential direction, for example, a portion(having a long distance to the end of the air flow passage)corresponding to a corner of a box-shaped outdoor unit 12. An outdoorunit 12 of a heat pump apparatus, namely an air conditioning apparatushaving an upstream portion including the second upstream expandingportion 5 d formed only in some portions of the circumferentialdirection of the bellmouth 5 is described below with reference to FIGS.9 to 11.

FIG. 9( a) is a front view of an outdoor unit of an air conditioningapparatus according to Embodiment 3 of the present invention. FIG. 9( b)is a cross-sectional view taken along the line D-D including itsrotation shaft. FIG. 9( c) is a cross-sectional view taken along theline E-E. FIG. 10 is a view showing the direction of an air passage, asseen from the rotational shaft. FIG. 11 is a partially enlargedcross-sectional view of a main section of a bellmouth and a propellerfan, as seen from an inlet side. In each figure the same referencenumerals and symbols are given to the same parts in Embodiments 1 and 2.Reference is also made to FIGS. 1 to 6 to describe below a blower.

An air conditioning apparatus, namely a box-shaped outdoor unit 12according to the present embodiment includes a blade 1 of a propellerfan 3 of its blower having a concave-shaped warpage (see FIG. 3) formedat the circumferential edge 1 c thereof so as to warp in a rotationaldirection 10.

As shown in FIG. 9( a), the bellmouth 5 surrounding the entire peripheryor the trailing edge of the propeller fan 3 has its upstream portionterminated at a first upstream expanding portion 5 c (see FIG. 4) in aportion extending in any of directions (i), (iii), (v), and (vii) asshown in FIG. 10, namely in a portion having a smaller distance to anair flow passage other than the bellmouth 5. In contrast, the bellmouth5 has a minimum inner diameter portion 5 b being face-to-face with thetrailing edge 1 b of the outer circumferential edge 1 c in a portiondefined by lines extending in the directions of (ii) and (iv) in asection consisting of a separating plate 22, a top plate 17, and abottom plate 18 and in a portion defined by lines extending in thedirections of (vi) and (viii) in a section consisting of a heatexchanger 15, the bottom plate 18, and the top plate 17, the minimuminner diameter portion 5 b being the closest to the outercircumferential edge 1 c of the blade 1 in a section from Pb2 to Pb3, asdescribed in Embodiment 1 with reference to, for example, FIG. 4. Thebellmouth 5 has a downstream expanding portion 5 a formed at a sectionfrom Pb2 to Pb1 so as to expand the air passage in the rotational shaftupstream direction. The air passage expanding shape (contraction flowshape as seen from the air flow direction) in the air inlet directionincludes a convex shaped first upstream expanding portion 5 c upstreamof the rotation shaft between Pb3 and Pb4, Pb3 being an upstream end ofthe minimum inner diameter portion 5 b. Also, the bellmouth 5 has aconcave shaped second upstream expanding portion 5 d from Pb4 to Pb5,which follows the first upstream expanding portion 5 c. The secondupstream expanding portion 5 d has a large curvature in the vicinity ofPb4, while it has a small curvature in the vicinity of Pb5, and has asubstantially conic section in the vicinity of Pb5. Furthermore, thebellmouth 5 has a convex shaped third upstream expanding portion 5 e ina section from Pb5 to Pb6, which follows the second upstream expandingportion 5 d.

As described in Embodiment 1, in the rotation shaft direction of thepropeller fan 3 and the bellmouth 5, Pb3, an upstream end of the minimuminner diameter portion 5 b, is located upstream of the trailing edge endPb2 in the outer circumferential edge 1 c in any of directions of (ii),(iv), (vi), and (viii). Pb4 in the transition between the first upstreamexpanding portion 5 c and the second upstream expanding portion 5 d islocated downstream of the rotation shaft direction of the maximumwarpage position Pf3 on the outer circumferential edge 1 c of the blade1. A position in the rotation shaft direction of the maximum warpageposition Pf3 on the outer circumferential edge 1 c of the blade 1 fallswithin the range covered by the second upstream expanding portion 5 d.

An air conditioning apparatus according to the present embodiment thatis an outdoor unit 12 is also characterized by the shape of thebellmouth 15 around the propeller fan 3 and the positional relationshipbetween the propeller fan 3 and the bellmouth 5. Accordingly, as withthe above described Embodiments 1 and 2, a great amount of air can bedrawn in from the outer circumferential edge 1 c of a blade 1 of ablower, which suppresses a pressure change on the surface of thebellmouth 5 arising from turbulence of the blade tip vortex 9.

A section between the upstream side of the second upstream expandingportion 5 d and the minimum inner diameter point Pb3 can be constructedwith a smoothly continued surface, which effectively suppressesturbulent air flow and efficiently reduces noise. In particular, in anoutdoor unit 12, the second upstream expanding portion 5 d and the thirdupstream expanding portion 5 e cover the periphery of the blade in anyof directions (ii), (iv), (vi), and (viii) as shown in FIG. 8 where adistance to an air flow passage other than the bellmouth 5 rapidlychanges in the circumferential direction, thereby efficientlysuppressing the fluctuation of incoming air flow and the blade tipvertex 9 as well as attaining reduction in noise.

Also, a change in air flow at the rotational position of the blade 1 canbe reduced, which results in reduction of a change of force exerted bythe propeller fan 3 on the fan motor 7, leading to reduction of bearingwear or shaft deflection of the fan motor 7. This prolongs thedurability of the outdoor unit 12 and helps to achieve the outdoor unit12 that provides a stable quality during a long period of service.

Since in the present embodiment, an upstream portion of the bellmouth 5including the second upstream expanding portion 5 d exists only at apart of the periphery direction of the outer circumferential edge 1 c,the effect of suppressing fluctuation of incoming air flow or the bladetip vortex 9 is reduced compared with above-described Embodiment 2 wheresuch a upstream portion is provided around the entire periphery.Instead, the diameter of the propeller fan 3 can be large. A propellerfan 3 having an increased diameter reduces the revolution of the fan fora required amount of air, leading to reduced noise. In addition, anincreased-diameter fan reduces the velocity of air flow blown out by thepropeller fan 3 and passing through the grill 16, leading to a reductionin noise emissions caused by the grill 16. So that low noise outdoorunit 12 can be obtained

Also, reduced velocity of air flow passing through the grill 16 resultsin reduced air flow resistance of the grill 16, leading to electricpower saving as well as the achievement of an highly energy-savingoutdoor unit 12. Furthermore, reduced air flow resistance of the grill16 leads to a reduction in a required pressure boost, resulting inreduction in noise emissions from the propeller fan 3 and resultantlower-noise outdoor unit 12.

As shown in FIG. 11 depicting a cross-section perpendicular to therotation shaft in the second upstream expanding portion 5 d, thebellmouth 5 has a convex-shaped end warpage 23 formed at bothcircumferential ends of the second upstream expanding portion 5 d in therotation shaft direction. This makes continuously smooth a transitionalsection between the second upstream expanding portion 5 d and a portionwhere no such portion is found, for example, between the direction of(vii) and that of (viii), or between the direction of (viii) and that of(I), thereby suppressing the fluctuation due to separation of the airflow coming into the bellmouth 5 in these transitional section, so thatlow noise effect can be easily obtained.

Embodiment 4

FIG. 12( a) is a front view of a rectangular box-shaped outdoor unit ofa heat pump water heater according to Embodiment 4 of the presentinvention. FIG. 12( b) is a horizontal cross-sectional view including arotation shaft taken along the line F-F. FIG. 12( c) is across-sectional view including a rotation shaft taken along the lineG-G. The reference numerals and symbols in FIG. 12 refer to the samecomponents as those in Embodiments 1 and 3. Reference is also made toFIGS. 1 to 6 to provide descriptions on the blower.

In a heat pump water heater, namely a rectangular box-shaped outdoorunit 25 according to the present embodiment, its blower has the samestructure as in Embodiment 3. Accordingly, descriptions on the blowerare omitted, and differences in structure from those in Embodiment 3 aredescribed below. As shown in FIG. 12, the heat pump water heateraccording to the present embodiment has an outlet face 13 provided inthe front of the outdoor unit 25, an external air inlet face 14 providedin two faces, that is, its opposing face (back face) and a face of theleft-hand side of the figure, and an L-shaped heat exchanger 15 isdisposed so as to cover the air inlet face 14. Also, a water heatexchanger 24 for performing heat exchange between a refrigerant andwater is provided at the bottom of the inboard air passage chamber 19.The water heat exchanger 24 occupies the bottom of the inboard airpassage chamber 19. When viewed from the propeller fan 3, the top plate24 a of the water heat exchanger 24 is replaced by the bottom plate 18in Embodiment 3. Therefore, the outdoor unit 25 of a heat pump waterheater according to the present embodiment also provides the sameadvantages and effects as the blower described in Embodiment 3, leadingto the implementation of the outdoor unit 25 which provides low-noiseand, preserves quality for a long period of time.

Embodiment 5

In addition to features described in Embodiment 1, a blower according tothe present embodiment is characterized in that a circumferential edgeof the blade 1 is warped toward an inlet side (α) from an outlet side(β). The shape of such a circumferential edge is described below interms of the warpage toward the inlet side from the outlet side.Features of a bellmouth 5 except the shape of the blade, the relativeposition of a propeller fan 3 and bellmouth 5, and the structure with afan motor 7 are the same as Embodiment 1. Accordingly, reference is alsomade to FIGS. 1 to 6 to provide a description on the blower.

FIG. 13 is an enlarged view, equivalent to FIG. 4, of a main section ofa blower according to Embodiment 5 of the present invention, wheredashed lines Ld1 to Ld11 are dividing meridians obtained by equallydividing a radial section of a blade with the rotation shaft being thecenter and rotating lines that connect divided points from hub side toan outer circumference side about the rotational shaft to project thedividing points to a plane containing the rotation shaft. The outercircumference side is shown. FIG. 13 shows 12 divisions ranging from theleading edge to the trailing edge. The dividing meridian is warped infront and at the back of a line Lf4 drawn in the outer circumferentialedge of a blade in such a manner that the outer circumferential edgecurves toward an inlet side (inlet space α) from an outlet side (outletspace β). Such a warpage shown in FIG. 13 is becoming greater at in themiddle between the leading edge and the trailing edge, Ld5 to Ld7, andis gradually becoming smaller toward the leading edge or the trailingedge, while no warpage is found at a leading edge 1 a and a trailingedge 1 b (represented as meridian in FIG. 13) that are ends of thedividing meridian.

A blower provided with a propeller fan 3 according to the presentembodiment having a blade outer circumferential edge warped toward theinlet side is described below in terms of its operation. As describedabove, the propeller fan 3, when driven by the fan motor 7, sends to theair outlet space β the air inside a region where the propeller fan 3rotates and at the same time draws in the air in the air inlet space αto the region where the propeller 3 rotates through surfaces defined bya leading edge 1 a or an outer circumferential edge 1 c when a blade isrotating.

Like FIG. 5, FIG. 14 is a view of an outer circumferential edge of ablade, with the addition of leader lines indicating the state of airflow in the vicinity of the outer circumferential edge of the blade. Asshown in FIG. 14, part of the air entering the propeller fan 3 becomes aleak flow 8 to the negative pressure surface 1 e from the pressuresurface 1 d via the outside of the outer circumferential edge 1 c. Inthe present embodiment, the outer circumferential edge of a blade iswarped toward an inlet side, which reduces the pressure differencebetween the pressure surface 1 d and the negative pressure surface 1 ein the outer circumferential edge 1 c as well as makes smooth the leakflow 8 coming into the negative pressure surface 1 e from the pressuresurface 1 d. Accordingly, a blade tip vortex 9 occurring at a positionalong the outer circumferential edge is on the negative pressure surface1 e, originating from the leak flow 8 occurring in the vicinity of theleading edge of the outer circumferential surface 1 c, has a highercentral pressure than those with no warped outer circumferential edgemade toward an inlet side, which causes the vortex to be weaker.

The blade tip vortex 9 grows as it transits to the trailing edge side 1b from the leading edge side 1 a, and moves away from the outercircumferential edge 1 c of the blade 1 at the maximum warpage positionPf3 at which a flow deflection becomes large. The blade tip vortex 9that left the outer circumferential edge 1 c is pushed by an entire flowfrom the inlet space α to the outlet space β and is discharged out ofthe blower, while it is weakening in vortex structure.

The vortex that left the outer circumferential edge 1 c interferes withthe bellmouth 5 and an adjacent blade causing noise emissions andimpedes air flow from the inlet space α to the outlet space β. For thisreasons, fan rotating speeds is increased to obtain a required amount ofair volume and pressure, increasing in noise emissions. Like the presentembodiment, the blade outer circumferential edge is warped toward anupstream side, thereby weakening the blade tip vortex 9 and suppressingincreased noise level caused by the blade tip vortex 9.

However, the blade tip vortex 9 becomes unstable such that its positionand vortex diameter are easily changed although it is weak as a vortexdue to its relatively high central when the outer circumferential edgeof the blade is warped toward the inlet side. For this reason, aconventional bellmouth 25 having only a first upstream expanding portionas shown in FIG. 15 cannot sufficiently obtain effects. As describedabove, actual blowers rarely have a wide area around the blade 1 in theair inlet space a and a circumferentially uniform shape. A bellmouth 24having a small first expanding portion indicated by a solid line issusceptible to fluctuation in the periphery, causing the weak, unstableblade tip vortex 9 to further become unstable, which disturbs a flowingpath and induces noise emissions. In contrast, in the case of thebellmouth 25 having a large first expanding portion indicated bydashed-dotted lines an influence of fluctuations in the periphery of theouter circumferential edge is mitigated. However, due to a narrow airpassage from the outer circumferential edge 1 c, air flow coming fromthe outer circumferential edge 1 c declines at the upstream side of therotation shaft direction, and at the same time a leak flow 8 from thepressure surface 1 d to the negative pressure surface 1 e also declines,resulting in a narrower region where the blade tip vortex 9 grows.Accordingly, if the warped outer circumferential edge techniqueaccording to the present invention is applied to this case, the bladetip vortex 9 becomes weak and therefore moves away from the bladeearlier. This tends to cause interfere with the bellmouth and itsadjacent blade and expand a disturbance in the flowing path, resultingin increased noise emissions. As described above, a combination of aconventional bellmouth and a propeller fan having warped outercircumferential edges cannot achieve maximum noise reduction effects.

As shown in FIG. 15 using dashed lines, in a blower according to thepresent embodiment having a convex-shaped first upstream expandingportion and a concave-shaped second upstream expanding portion formed atthe upstream side of the rotation shaft, the bellmouth 5 covers area ofthe outer circumferential edge 1 c of the blade 1 and provides a greaterdistance to the outer circumferential edge 1 c of the blade 1 than aconventional bellmouth indicated by solid lines or dashed-dotted lines.This makes circumferentially uniform air passage around the outercircumferential edge 1 c of the blade 1, thereby suppressingfluctuations of the air flow coming into the blade 1 and unstable bladetip vortex as well as allowing more air flow to be taken in from theouter circumferential edge 1 c of the blade 1 and preventing the bladetip vortex 9 from moving away. Consequently, a propeller fan 3 havingthe warped blade outer circumferential edge can effectively achievenoise reduction effects, leading to the achievement of a low-noiseblower.

The warpage of the outer circumferential edge made toward the inlet sidefrom the outlet side, as shown in FIG. 13, is becoming greater in themiddle between the leading edge 1 a and the trailing edge 1 b and isgradually becoming smaller toward the trailing edge 1 b, while nowarpage is found at the trailing edge 1 b, an end of the dividingmeridian. As described above, the bellmouth 5 causes less air flow tocome from the outer circumferential edge 1 c of the blade 1, and theless warped outer circumferential edge at the trailing edge 1 b wherethere is less leak flow 8 where the blade tip vortex 9 originates andgrows results in a greater turning angle at an outer circumferentialedge having a high circumferential velocity, thereby effectivelyheightening blade boosting. This reduces the rotating speed for arequired amount of air volume and pressure, resulting in a reduction inrelative velocity of air flow on the blade surface. Such a reduction inrelative velocity of air flow on the blade surface means a reduction inpressure change which causes noise emissions, leading to the achievementof a low-noise blower.

Embodiment 6

A heat pump apparatus, for example, an air conditioning apparatus isdescribed with reference to FIGS. 7 and 8 provided with a blower, with ablade outer circumferential edge of a propeller fan 3 being warpedtoward an inlet side from an outlet side, having a second upstreamexpanding portion 5 d along the entire circumference in thecircumference direction continuously upstream of the first upstreamexpanding portion of the bellmouth 5. Reference to FIGS. 1 to 6 is madeto describe the blower.

An air conditioning apparatus to which a blower according to the presentembodiment is applied has the same structure and operation as thosedescribed in Embodiment 2, and provides the same advantages and effectsas those in Embodiment 2. Accordingly, descriptions provided below aremainly regarding warped outer circumferential edge of a blade 1 of thepropeller fan 3.

As described above, a conventional bellmouth structure cannot providesufficient effect even if the blade 1 of the propeller fan 3 has awarped outer circumferential edge toward the inlet side. In particular,when installed in a heat pump apparatus such as an air conditioningapparatus, a conventional bellmouth structure has difficulties inproviding noise reduction effect resulting from a blade having a warpedouter circumferential edge, due to low circumferential uniformity in airpassages at the periphery of the blade circumferential edge.

An air conditioning apparatus according to the present embodimentincludes a bellmouth that has a first upstream expanding portion and asecond upstream expanding portion provided at the entire circumferencethereof and a propeller fan 3 that has an outer circumferential edge ofits blade 1 warped toward an air inlet side, which suppresses the effectof non-uniform air passage around the outer circumferential edge andensures the entry of air from the outer circumferential edge 1 c as wellas weakens a blade tip vortex 9 and achieves noise reduction effects,leading to the achievement of a low-noise heat pump apparatus.

Embodiment 7

Descriptions will be given to a heat pump apparatus, for example, an airconditioning apparatus provided with a propeller fan 3 having a outercircumferential edge of its blade warped toward an inlet side from anoutlet side and a second upstream expanding portion 5 d formed alongpart of the circumference continuously upstream side of the firstupstream expanding portion 5 c, Reference to FIGS. 1 to 6 is made todescribe the blower.

An air conditioning apparatus to which a blower according to the presentembodiment is applied has the same structure and operation as thosedescribed in Embodiment 3 using FIGS. 10 and 11, and provides the sameadvantages and effects of Embodiment 3. Accordingly, descriptionsprovided below are mainly regarding warping outer circumferential edgeof a blade 1 of the propeller fan 3 toward the inlet side.

As described above, a conventional bellmouth structure cannot achievesufficient effects even if a blade 1 of a propeller fan 3 has a warpedouter circumferential edge toward the inlet side. In particular, wheninstalled in a heat pump apparatus such as an air conditioningapparatus, uniformity is low in the air passage around the outercircumferential edge of the blade. When adopting a large outer diameterof the fan, the distance between ambient faces and the blade becomessmall, so that it is difficult to obtain low noise effect in the case ofwarping the outer circumferential edge of the blade toward the inletside.

An air conditioning apparatus according to the present embodimentincludes a bellmouth that has a first upstream expanding portion and asecond upstream expanding portion provided at a location in which thereis a significant change in distance between the blade and the surface ofthe apparatus, as viewed from the rotating blade, which effectivelysuppresses the effect of un-uniform air passage of the outercircumferential edge and ensures the entry of air from the outercircumferential edge 1 c as well as weakens a blade tip vortex 9 andachieves noise reduction effects, leading to the achievement of alow-noise heat pump apparatus.

FIGS. 16 and 17 are graphs showing the relationship of air volume andaerodynamic noise level by combining cases of an outdoor unit of an airconditioning apparatus having a blade 1 of a propeller fan 3 with andwithout a warped outer circumferential edge, second upstream expandingportion upstream of the bellmouth first upstream expanding portion in acorner consisting of a separation plate, a top plate, and a bottom plateof the outdoor unit, and those having a conventional bellmouth. Theouter circumferential edge of a blade 1 has a different shape betweenFIG. 16 and FIG. 17. Blade shapes in FIGS. 16 and 17 are hereinafterreferred to as propeller fan A and propeller fan B, respectively.

Warpage of the propeller fan A and the propeller fan B is concretelydescribed below. FIG. 18 shows dividing meridians, like those in FIG.13. A θ being an angular difference between before and after theinclination of the dividing meridian changes, in the propeller fan A, θat a dividing meridian in the middle of the leading edge 1 a and thetrailing edge 1 b, that is, a dividing meridian Ld6 in FIG. 18 is set ata maximum of about 14 degrees. In the propeller fan B, θ at a dividingmeridian closer to the leading edge 1 a, that is, a dividing meridianLd4 in FIG. 18 is set at a maximum of about 14 degrees. Radius positionwhich is a base point where the gradient of the dividing meridianchanges is specified as 85% radius of the outer circumferential diameterfor both fans. The maximum θ value (about 14 degrees) is obtained aftervarious tests are conducted and preferably approximately 14 degrees.FIG. 19 is a development view of the outer circumferential edge of ablade 1. Warpage ratio is defined as D divided by L, where D is amaximum distance between the blade chord and the blade and L is thelength of the chord. Warpage ratio is set to 5.8 percent at a position85 percent of the radius and to 8.7 percent at a position of the outerdiameter.

Both of FIGS. 16 and 17 shows that a bellmouth having a second upstreamexpanding portion provides more noise reduction than a conventionalbellmouth in the case where no warpage is formed in the outercircumferential edge of a blade. In the case where a warpage is formedin the outer circumferential edge of a blade toward the inlet side, theconventional bellmouth provides nearly no noise reduction for an outdoorunit, while a bellmouth having a second upstream expanding portionprovides a significant noise reduction.

INDUSTRIAL APPLICABILITY

An outdoor unit 12 of an air conditioning apparatus and an outdoor unit25 of a heat pump water heater are described above as an example ofapplications of a blower according to the present invention. The bloweraccording to the present invention can be widely used in other varioustypes of apparatuses (for example, a ventilating fan) and facilitieswhich are provided with a blower.

1. A blower comprising: a blade having an outer circumferential edgehaving a recessed warp in a rotational direction, and an annularbellmouth covering the circumference of the blade at an air outlet side,wherein a portion of the bellmouth facing a face composed of arotational trajectory of the outer circumferential edge has a firstupstream expanding portion formed in a shape of a convex, facing anupstream direction of a rotation shaft and extending upstream from aminimum inner diameter position and a second upstream expanding portionformed in a shape of a concave, facing the upstream direction of therotation shaft, being continuous with and extending upstream from thefirst upstream expanding portion.
 2. The blower of claim 1, wherein anupstream portion of the second upstream expanding portion is formedgenerally in a shape of a cone.
 3. The blower of claim 1, wherein atransition between the first upstream expanding portion and the secondupstream expanding portion is located downstream of a maximum warpageposition on the outer circumferential edge of the blade.
 4. The blowerof claim 1, wherein a third upstream expanding portion is formed in ashape of a convex in the upstream direction of the rotation shaft, thethird upstream expanding portion being continuous with and extendingupstream from the second upstream expanding portion.
 5. The blower ofclaim 4, wherein the second upstream expanding portion or the thirdupstream expanding portion covers the maximum warpage portion on theouter circumferential edge of the blade.
 6. The blower of claim 1,wherein an outer circumferential edge side of the blade of a propellerfan is warped toward an inlet side from an outlet side.
 7. The blower ofclaim 6, wherein regarding a warp formed from the outlet side toward theinlet side in the outer circumferential edge side of the blade of thepropeller fan, a degree of the warp becomes gradually smaller from amiddle point between a leading edge and a trailing edge toward thetrailing edge.
 8. A heat pump apparatus comprising: an air outlet faceprovided on a top face or a side face of an enclosure and disposing ablower thereon, an air inlet face provided on at least one face exceptthe air outlet face, a heat exchanger disposed so as to cover the airinlet face; and a plurality of side plates to form the other facesexcept the air outlet face and the air inlet face, wherein the blowerincludes a blade having an outer circumferential edge having a recessedwarp in a rotational direction and an annular bellmouth covering thecircumference of the blade at an outlet side; and wherein a portion ofthe bellmouth facing a face composed of a rotational trajectory of theouter circumferential edge has a first upstream expanding portion formedin a shape of a convex, facing an upstream direction of a rotation shaftand extending upstream from a minimum inner diameter position at anentire portion of a circumferential direction of the bellmouth and asecond upstream expanding portion formed in a shape of a concave, facingthe upstream direction of the rotation shaft, being continuous with andextending upstream from the first upstream expanding portion at anentire portion of the circumferential direction of the bellmouth.
 9. Theheat pump apparatus of claim 8, wherein an upstream portion of thesecond upstream expanding portion is formed generally in a shape of acone.
 10. (canceled)
 11. A heat pump apparatus comprising: an air outletface provided on a top face or a side face of an enclosure and disposinga blower thereon, an air inlet face provided on at least one face exceptthe air outlet face, a heat exchanger disposed so as to cover the airinlet face; and a plurality of side plates to form the other facesexcept the air outlet face and the air inlet face, wherein the blowerincludes a blade having an outer circumferential edge having a recessedwarp in a rotational direction and an annular bellmouth covering thecircumference of the blade at an outlet side; and wherein a portion ofthe bellmouth facing a face composed of a rotational trajectory of theouter circumferential edge has a first upstream expanding portion formedin a shape of a convex, facing an upstream direction of a rotation shaftand extending upstream from a minimum inner diameter position at anentire portion of a circumferential direction of the bellmouth and asecond upstream expanding portion formed in a shape of a concave, facingthe upstream direction of the rotation shaft, being continuous with andextending upstream from the first upstream expanding portion at someportions of the circumferential direction of the bellmouth.
 12. The heatpump apparatus of claim 11, wherein an upstream portion of the secondupstream expanding portion is formed generally in a shape of a cone. 13.The heat pump apparatus of claim 11, wherein the second upstreamexpanding portion of the bellmouth has a curved surface at bothcircumferential ends thereof, the curved surface being formed in a shapeof a convex in the direction of a rotation shaft.
 14. The heat pumpapparatus of claim 11, wherein a circumferential position of thebellmouth where the second upstream expanding portion partly extendsupstream from the first upstream expanding portion corresponds to acorner between side faces surrounding the air outlet face of theenclosure.
 15. The heat pump apparatus of claim 14, wherein the sidefaces surrounding the air outlet face of the enclosure consist of theplurality of side plates.
 16. The heat pump apparatus of claim 14,wherein the side faces surrounding the air outlet face of the enclosureconsist of the plurality of side plates and the heat exchanger. 17.(canceled)